Next-generation communication systems have introduced at least one Relay Station (RS) that relays communication between a Base Station (BS) and a Mobile Station (MS) to expand coverage and enable communication in a shaded area while reducing power consumption of the MS. The RS transmits/receives signals on a subframe basis, and the subframe includes a Physical Control Format Indicator Channel (PCFICH) and a Physical Downlink Control Channel (PDCCH) carrying control information, and a Physical Downlink Shared Channel (PDSCH) carrying real data. Control information on the PCFICH/PDCCH and data on the PDSCH are transmitted by Time Division Multiplexing (TDM).
FIG. 1 illustrates a data transmission/reception operation in an RS communication system according to the present disclosure.
Referring to FIG. 1, the RS communication system includes a BS 101, an RS 103 and an MS 105. The BS 101 transmits a data signal S1 110 to the RS 103 for a time period T1, and after receiving the data signal S1, the RS 103 transmits a data signal S2 120 containing details of the S1 to the MS 105 for a time period T2. The MS 105 recognizes the RS 103 as one independent BS.
Because of the difficulty in communicating with both the BS 101 and the MS 105 using the same frequency resource, the RS 103 uses different time resources, e.g., time periods T1 and T2, for reception of the data signal S1 and transmission of the data signal S2 as shown in FIG. 1.
As such, the conventional RS communication system fixedly divides resources of a specific time period and uses them for signal exchanges between the RS and the BS, and between the RS and the MS, preventing effective use of the resources. For example, during a subframe allocated for data transmission from the BS to the RS, the conventional RS should wait for reception of data transmitted from the BS even if there is no data transmitted from the BS, making its data transmission to the MS impossible. So, during the subframe allocated for data transmission from the BS to the RS, no data can be transmitted undesirably. For these reasons, studies are made of RS communication systems capable of efficiently using resources.